Television system



NOV. 6, 1934. R GOSHAW I 1,979,463

TELEVISION SYSTEM Filed May 11, 1932 ElE l TO AMP.

TO SCREEN. TO AC. 3 5/ 1 INVENTOR II'l H. Gnshaw AMP.

Patented Nov. 6, 1934 1,979,463 TELEVISION (SYSTEM,

Irl R. Goshaw, Nutley, N. J., 'assignor to Wired Radio,Inc., New York,N. Y., a corporation of Delaware Application May 11, 1932, Serial No.610,546

7 Claims. (Cl. 178-6) This invention'relates to television systems andparticularly to such systems of the non-mechanical type wherein nomechanical movements are employed although such movements may besubstituted for non-mechanical elements if desired.

An object of the invention is to transmit images of objects withelectrical currents. V Another object of the invention is to generateand transmit currents. corresponding to the light and shade densities ofan object and to translate such currents into light images'of saidobjects at. a distant point. I e

I A'further object of the invention is to transmit light images ofobjects with a system employing g non-mechanical movements. V.

A still further object of the invention is to provide atelevision-system for transmitting imagesbytransmitting only certainportions of an image characterized by a certain light density.

In the usual type of television transmission system, an object or imagethereof isscanned by a flying light spot orfelectron streamto analyzethe object or image into .unitv areas ,for serial transmission tosimilar apparatus for building up the image in the same. oran,.-equivalent man.-

ner. These systems have. many'disadvantages such as the frequencylimitation of theapparatus.

the .difiiculty of synchronizing moving elements at. the transmitterandreceiver, the difiiculty in obtaining suflicient detail and gooddefinition because of the rapid movement and short duration .of a unitlight area, and, where mechanical moving elements are employed, thevlimitation'by speed and size to a small picture area.

,35 The television system disclosed hereinafter requires a lessefficient line then the present type since the linecarries lessload forthe same detail as now obtained while the size of thepicture' is notlimited because no mechanical movements are employed for analyzing orbuilding up-the images.

' Synchronization is natural in that the house supply current may supplythe transmitterand receiver directly, or synchronization may be obtainedby simple tuning as in a radio receiver.

It is to be understood that mechanical elements may be substituted forcertain electrical elements,

these mechanical elements being of so simple a nature that they may betaken bodily from present pictureprojection systems nowin general use.

The chief principle of. the invention is the electrical delay ofcurrents so that a serial re- .lationship isproduced from a plurality ofgenerators operatingsimultaneously. For instance,

@a composite cathode of a photoelectric cell is employed, .thecathodebeing formedqf many inthe output I of the transmitter; and, 'Fig: 5 isacircuit element which may be sub- PATENTMOFFICE} dividualcells having acommon anode, each cell employed in which a picture is obtained byvoltageflashes, at the proper rate of speed modified byv the incomingpicture currents.

The invention will be more fully understood from the followingdescription read in conjunction with the accompanying drawing in which:.Fig. 1 is a diagrammatic view of the transmission system Fig. 2 is adetailed-plan view of a cathode of the photoelectric cell: 7 I

Fig. 31s a diagrammatic view of the receiving apparatus:

Fig. 4 is a graph of the television currents in stituted for a portionof Fig. 3.

Referring specifically to Fig. 1, an object. 0 is illuminatedwithintermittent light from a lamp 5 supplied by an alternator 6 or fromthe house supply source. The image of the object so produced is focussedby a lens 8 upon a composite cathode 9 of a photoelectric cell having ananode 10.. The projecting lamp produces on the cathode 9intermittentlight'images which occur at double thefrequencyof the source6. Intermittent images may also be produced on the cathode with aconstant illumination of the object 0 but which is broken up by ashutter 12 operated byany means welll znown in the art.

In Fig. 2 a plan View of the cathode 9 of the photoelectric cell shows'acathodedivided up into a pluralityof sections which are insulated fromone another by thin insulatingpartitions such as lavite or mica. The.back of the cell is formed of sections of conducting material insulatedfrom oneanother but which-have deposited thereon the 1 photosensitivematerial. This construction forms many individual photoelectric cellsindependent of one another electrically but which have a common anode10. To each cell unit is connected a conductor and as shown in Fig. 1they are brought out to a common lead or busbar 14. In all conductorsbut one there are inserted delay elements 16, such as inductances ofgraduated values which have the proper amount of distributed capacity toproduce a smalldifference in delay in each circuit. To'maintain thedirect current impedances in eachcircuit constant there is also insertedin the conductors a graduated series of pure resistances the directionof. graduation being the re- .y e rse of {the delay element 16. Asstated above.

the conductors terminate in a busbar 14 connected to the input of anamplifier 20, the other input lead being connected to the anode 9 of thephotocell by conductor 21. The output of the amplifier is fed into atransmitter 22, from which it may be broadcast over an antenna 23, orwire conductors 24.

The operation of the transmitter is as follows: Intermittent images atany desired rate such as twenty per second, which is the presenttransmission rate, or highen are impressed upon the cathode 9. At eachimage impression the unit areas receiving light above a certain densitywill simultaneously generate currents proportional to, the light fallingthereon. The generated impulses will not arrive at the amplifier 20simultaneously, however, but in a serial order, the time unit be. tweenthe first and last impulsedepending upon the delay inserted in eachparticular circuit. The amount of delay is determined by the period ofillumination of the cathode and the number of unit cells or areasemployed. With present standard television practice, the'number ofindividual cells would be'in the neighborhood of- 3600 and theintermittent illumination at the rate of twenty per second, making thedelay in each circuit on the order of 1/72000 of a second. The amount ofof the lightimpulses is immaterial as will'be seen later but a sharp'impression of the impulses'upon the cathode is required.

In Fig. 4 a time interval between the impression of light impulses isshown which may be an interval of 1/20 ofa second between 'd and b, thefirst and last impulse' respectively. The variation in the currentarriving at the amplifier 2 0 is shown by this curve. The portion -ofleocurrent near the middle of the intervalis indicare f a ar a ea' hh hg ar ss the i l of the cathode sucn'a wquiaberdrmea by"tl'1 e object o withthe delay graduated in' a'verti'al diy q ig eferring now to thereceiving apparatus in Fig, 3, an antenna 3Q or wire conductors31'impress incoming energy upon a receiver 32. After iduct-lion to theoriginal" impulses in the receiver they are amplified in" an amplifier34 is'conn'ectedtd'a busbar 35an'd'conductor 35. The receiving screen isin appearance similar to'the cathode of Fig. 2 but theelement'a'ry areasare formedof either individual neon lamps or incandescent lamps whichhaveeom'monelectrodes 3'7 and lOQ The otherelectredesor grids of thelamps are conneeted 't'dtlie busbar 35 through iilhy circuits 38" havingvar ing amounts of delay and pure resistancesf39 identicaltothearrangement in'Fig. 1. H e wee the common electrode lead 36 andelectrode 37 there isconnected'a sourceof direct potential ll shunted bya'variable condenser 42, a variable inductive element '43 and a'variableresistance 44; These three elements shown within the dotted lines serveas the trigger for the receiving screen and provide, in connection withthe neon lamps, a relaxation oscillator systernj That is, a voltage fromsource il will build up to the poin of flash rs? and the di ch g of sieEel #2 will li ht t e amps for an ihsthht This in val hf ope at on de ed upo t ihs .e the elem n 2 43 an an mar'be ar ed With n Wi d l mit th slaxat on eh b in wellkhowh in the art Fig- 5 shows a etailed irc i wh hmay h h ii hted f th w ich O Fi 3 s w Within the d tted l ne ri oth werll h rslhXhtion oscillator circuit. A source of direct'current potentialis connected between the screen and amplifier through a contact 51shunted for condenser 52 by protecting the contacts 51. The contacts 51are operated by a relay 54 which may be connected to the ordinary cyclealternating current house supply. The relay may be made to operate thecontacts 51, 6( times per sec- 0nd or 120 times per second by a directconnection to the house tap. The receiving screen when used with thecircuit of Fig. 5 may be either individual neon lamps, incandescentlamps, or in fact, merely arc gaps across which a current will flow atthe proper voltage.

The operation of the receiver is as follows: The train of impulses shownin Fig. 4 arrive at the busbar 35 and conductor 36 after detection andamplification. As the impulses arrive they are delayed in proportion tothe amount of delay in each individual circuit which is the same as thedelay in the circuits at the transmitter. If we assume an impulse a asthe first impulse, that particular impulse will arrive at the receivingposition a on the screen at a certain instant of time. That same impulseoi course, will arrive at the other light producing positions previous,to

.its arrival at the position a butwill b e dissiatch will the d dhh Wantthe oth Posit on rr r h Takin h r ceiving cell conductor that has nodelay whatever, which in this case is impulse b orthe last impulse, allof the preceding impulses will arrive a he i h l men q e the as im andwill'be dissipated, However, at a certain instant of time every impulsewill be at its proper element, which, with the assurned f gures above.will be 1/20 of a second after the first impulse arrives at the busbar35. At this instant 9. volt a w l b b l u f o the hhrc 1 su fic o as then n m twe the elev e 3' nd 0., e volta e n ds det rm ni the lightintensities of the unit areas, or the COD- tact 51 will be closed toconnect the source 50 to the screen' Other sources of light such asincandesce a p and the cqo 'din te ys em f ar gaps are preferable withthe circuit of Fig. 5.

The common voltage irnpresse dis suflicient to light all lamps with thesame intensity but be.- cause of the supplementing of the common voltagewith the incoming impulse voltages at the vario amps ach li ht willproduce vary intensities corresponding to the light and shade densitiesof the object. When the lights are flashed by the common voltage animage will be observed on the screen corresponding to that projected onthe cathode 9 at the transmitter. It is not necessary that the lamps beextinguished ior the dark portions of the object, as long as there is avariation between the elements so that the brighter ones cause thelighter ones to appear as darker portions.

"In the system above described, it is to be observed that by using thelamp source 5 connected to the alternating house supply, the object 0may be illuminated 60 times a second by using a rectifier, or 120 timesper second without the rectifier'. Thus illuminated there will be sentto the receiver a train of impulses 6Q and 120 times per second,respectively, each train comprising an image. The circuit of Fig. 5 isespecially desirable at the receiver in this case, the relay 54 beingsimilarly controlled to make contact ,60 or 12;) times per second by theordinary house current sh ol ih th y chr n in P obl area uppli d omcommon p wer s s e ii- At t is 'rate, flicker is absolutely eliminated.In using the relaxation oscillator it is only necessary to vary thetuning of the elements making up the oscillators in a manner similar tothe tuning of any radio receiver. The transmitting apparatus using theshutter type of light interrupter may be simply that of a moving picturecamera or projector which can be operated manually or by a spring motorwell known in the motion picture art. With the convenient tuningoperation at the receiver, the manual or motor drive is easilysynchronized. It is to be understood that the receiver may operatewithout a trigger system. That is, a constant voltage sufficient toenergize the lamps to a certain brightness is applied to the screen anda shutter similar to the one at the transmitter or of the multipleopening type exposes the lamps to View at the instant the p pilluminating voltages are present at the lamp The invention has beendescribed to emphasize such advantages as non-mechanical apparatus,simplicity of operation, the method of operation which provides positivedetail for each individual element, and the efficient use oftransmission lines since only the light portions of the object aretransmitted. The scope of the invention is defined by the appendedclaims.

What is claimed is:

1. In an electrical transmission system for transmitting currentscharacterized by the li t and shade intensities of an object, thecombination of means for simultaneously obtaining a plurality ofcurrents proportional to the light intensities of unit areas of animage, electrical delay networks for distributing said currents in atransmission line in a serial order, and electrical delay networks forimpressing said currents upon a plurality of light producing devicessimultaneously.

2. An electrical transmission system for the transmission of currentscorresponding to the light and shade intensities of an object, means forsimultaneously producing currents corresponding to the light intensitiesof a plurality of unit areas of an object, electrical delay networks fordelaying the transmission of said currents in a graduated order, meansfor transmitting said currents to a receiving point, a plurality oflight producing elements at said receiving point, and electrical delaynetworks for delaying said currents in the reverse graduated order forsimultaneously impressing on said light producing elements energycorresponding to the light intensities of the unit areas at saidtransmitter.

3. In a television system, a composite cathode comprising a plurality ofindividual unit sections, means for intermittently impressing an imagethereon, an electrical delay network for impressing the currentsgenerated from said unit section in serial order on a transmission line,a plurality of light producing elements at a receiving point at theterminal of said transmission line, and a plurality of individualcircuits including electrical delay elements connected to said lightproducing elements for simultaneously impressing upon said elements thecurrents generated by the light affected sections of said compositecathode.

4. In a television system, the combination of a composite cathode havinga plurality of individual light sensitive areas, an anode for all ofsaid areas, means for impressing an image on said cathode intermittentlyfor producing electrical impulses, a transmission line, an electricaldelay network connected to said line for impressing the impulses fromsaid cathode upon said transmission line at definite mutually exclusiveinstants of time, a receiver at the terminal of said transmission line,and a similar network at said receiver for re-arranging said impulses sothat they appear simultaneously.

5. In a television system, means for simultaneously obtaining electricalimpulses corresponding to the light intensities of a plurality of unitareas of an object, a single channel transmission line, an electricaldelay network connected to said line for transmitting said impulses oversaid single channel transmission line while maintaining a separationbetween impulses, a plurality of light producing elements'correspondingto unit areas at said first means, and a similar network connected tosaid transmission line for simultaneously impressing said impulses onsaid light producing elements in accordance with their generation atsaid first means.

6. In a system for transmitting currents characterized by the light andshade intensities of an object, the combination of a plurality of photosensitive means for producing electrical currents, means forilluminating said object from an alternating current source, atransmission line, an electrical delay network connected to said linefor distributing the currents from said plurality of photo sensitivemeans in said transmission line in a serial order, a plurality ofsources of light for reproducing an image of said object, an electricaldelay network connected to said line and to said light sources fordistributing said currents to said light sources simultaneously, andmeans connected to said plurality of light sources for actuating saidlight sources from an alternating current source.

7. An electrical transmission system for the transmission of currentscorresponding to the light and shade intensities of an object, means forsimultaneously producing current impulses corresponding to the lightintensities of unit areas of an object, means for illuminating saidobject with light from a source energized from an alternating currentsource, an electrical delay network for distributing said impulses fromsaid first mentioned means in a serial order between the nodes of thecurrents in said alternating current source, means for transmitting saidcurrents to a receiving point, a plurality of light producing elementsat said receiving point, an electrical delay network for distributingsaid impulses in reversed order on said light producing elements, andmeans connected to an alternating current source for controlling theactuation of said light producing elements, the production of saidcurrents and the reproduction of the received image of the object beingin synchronism, when said alternating current sources have the samefrequency.

IRL R. GOSHAW.

